Farrukh, Faiqa

Abstract Background Systemic mastocytosis (SM) is formally classified as advanced, smoldering (SSM), or indolent (ISM). Advanced SM indicates the presence of an associated non-mast cell lineage hematologic neoplasm (SM-AHN) or at least one "C finding" (i.e. features of organopathy from mast cell infiltration); the latter defines aggressive SM (ASM). Both advanced SM and ISM might be associated with MC mediator symptoms (MC-MSs) or urticaria pigmentosa (UP). Current drug therapy for SM is primarily directed at reversing C findings or alleviating symptoms/UP, and includes cladribine, midostaurin, and avapritinib. The former has a long track-record of safety while the latter two are recent additions that target the associated KIT mutation, but with concerning gastrointestinal and neurological side effects. We retrospectively reviewed our experience with cladribine therapy in SM, in order to maintain a proper perspective in making treatment choices. Methods The current study includes 42 patients with SM (22 advanced and 20 indolent/smoldering), recruited from the Mayo Clinic SM database, based on documentation of treatment with cladribine. Conventional criteria were used for diagnosis and classification (Blood 2016;127:2391) and definitions of response (Eur J Clin Invest. 2007 Jun;37(6):435); in the latter regard, we utilized modified Valent criteria that incorporated a minimum of one-month duration to qualify as response. Results Advanced SM: 22 patients (median age 65 years, range 48-80; males 68%) had advanced SM, including 13 SM-AHN, 8 ASM, and 1 mast cell leukemia. Median (range) BM MC burden was 30% (10%-90%), serum tryptase 193 ng/ml (21-1370), hemoglobin 10.6 g/dL (7-15), leukocytes 6 x 10(9)/L (0.5-63), and platelets 115 x 10(9)/L (8-320). KITD816V was detected in 86% of 19 evaluated and abnormal karyotype in 14% of 21 evaluated. 50% of patients had palpable hepatomegaly, 59% palpable splenomegaly, 100% MC-MSs, and 14% UP; 87% displayed at least one C finding. Median time from BM biopsy confirmed diagnosis to initiation of cladribine therapy was 1.5 months (range 0.1-17). 55% of patients received at least 3 cycles of treatment. Overall response (OR) was documented in 17 (77%) patients with similar OR rates in ASM (88%) vs SM-AHN (69%; p=0.32), with median time to response of 3.7 months (range 0.4-9). OR included 45% major response (MR) and 32% partial response (PR). 17 patients were evaluated for BM MC response with 44% showing >50% reduction, in MCs, including 19% with complete resolution. Organomegaly response was complete in 36% and partial in 27%. Tryptase response of >50% was documented in 32%. Cladribine side effects were limited to cytopenias with 36% showing grade 3 or 4 myeloid cytopenia. Median duration of response was 6 months (range 1-67). Six patients, including 5 with SM-AHN, progressed to either AML or MCL. Among the 5 patients who did not respond to cladribine, one with ASM was successfully treated with midostaurin. Indolent or smoldering SM: 20 patients (median age 56 years, range 36-73; males 45%) had ISM (n=17) or SSM (n=3). Median (range) BM MC burden was 13% (5%-60%) and serum tryptase level 49 ng/ml (14-1630). KITD816V was detected in 95% of 19 evaluated patients and abnormal karyotype in 12% of 17 evaluated. All patients displayed MC-MSs and 46% UP. Median time from BM biopsy confirmed diagnosis to initiation of cladribine therapy was 4 months (range 0-92). 85% of patients received at least 3 cycles of cladribine therapy. OR was documented in 14 (70%) patients, including 60% complete or major regression of symptoms or UP, with median time to maximal response of 8.5 months (range 1-98); response rates in patients with UP were similar with 57% complete or major regression; 10 patients were evaluable for BM MC response with 50% showing >50% reduction in MC burden. Serum tryptase response was evaluated in 13 patients with 46% showing >50% reduction in levels. Treatment-emergent cladribine side effects were limited to cytopenias with only 3 (15%) patients experiencing grade 3 or 4 myeloid cytopenia and (n=3; 15%) and 6 (30%) experiencing grade 3 or 4 lymphopenia. Conclusions: The current study confirms the favorable side effect profile and long-term safety of cladribine as a first-line drug of choice for both indolent and advanced SM. Response to cladribine therapy was evident in all aspects of the disease, including MC-associated organopathy, UP, MC-MSs, serum tryptase level and bone marrow MC burden. Disclosures Patnaik: StemLine: Research Funding; Kura Oncology: Research Funding. Al-Kali: Novartis: Research Funding; Astex: Other: Research support to institution.

Abstract Background In addition to its influence on survival, leukocytosis in myeloproliferative neoplasms (MPN) has also been implicated as a risk factor for thrombosis, including venous thrombosis in PV (Blood Cancer J, 2017;7:662) and arterial thrombosis in ET (Blood. 2011;117:5857). In the current study, we sought to clarify the individual prognostic contribution of absolute neutrophil (ANC), lymphocyte (ALC) and monocyte (AMC) counts, for arterial and venous thrombotic events in essential thrombocythemia (ET) and polycythemia vera (PV). Methods The current study included 487 patients with ET (n=349) or PV (n=138), recruited from the Mayo Clinic MPN database, based on availability of information on ANC, ALC and AMC. Conventional criteria were used for diagnosis (Blood 2016;127:2391) and definitions of major vascular events (Blood Cancer J. 2018;8:25). Conventional statistical models were applied using JMP Pro 14.0.0 software package, SAS Institute, Cary, NC. Multivariable analyses included previously established risk factors for arterial or venous thrombosis. Results Essential thrombocythemia patients: 349 patients (median age 57 years, range 18-89; females 61%) with ET were included in the study: 46% JAK2, 34% CALR, 16% triple-negative and 4% MPL mutated; IPSET risk category high 24%, intermediate 41%, and low 35%; presenting median (range) values were 13.8 g/dL (11.1-16.4) for hemoglobin, 8.2 x 10(9)/L (3.2-52) for leukocyte count, and 859 x 10(9)/L (451-3460) for platelet count; palpable splenomegaly was present in 48 (14%) patients and cardiovascular risk factors in 56%; median follow-up was 10 years (range 0-47). There were 38 (11%) documented venous events at diagnosis and 31 (9%) after diagnosis and 42 (12%) arterial events at diagnosis and 64 (18%) after diagnosis. Polycythemia vera patients: 138 patients (median age 62 years, range 20-94; females 50%) with PV were included in the study; presenting median (range) values were 17.9 g/dL (16.1-24) for hemoglobin, 11.8 x 10(9)/L (2.7-65.8) for leukocyte count, and 434 x 10(9)/L (44-1679) for platelet count; 57% of patients presented with leukocytosis >11 x 10(9)/L; palpable splenomegaly was present in 37 (27%) patients; abnormal karyotype was documented in 17% of patients. Median follow-up was 11 years (range 0.03-36.7). There were 22 (16%) documented venous events at diagnosis and 21 (16%) after diagnosis and 28 (20%) arterial events at diagnosis and 15 (11%) after diagnosis. ANC/ALC/AMC associations with thrombosis in ET and PV: In both ET and PV, ANC/ALC/AMC did not correlate with arterial thrombosis at/prior to diagnosis (p>0.1 in all instances). By contrast, in both ET and PV, higher ANC (p=0.05 and 0.04, respectively) and higher AMC (p=0.005 and 0.07), but not ALC (p=0.6 and 0.7), were correlated with venous thrombosis at/prior to diagnosis. Arterial thrombosis-free survival was not affected by ANC/ALC/AMC in either ET or PV (p>0.1 in all instances). By contrast, venous thrombosis-free survival in both ET and PV was compromised by higher ANC (p=0.05 and 0.003, respectively), but not ALC or AMC. The significant association between higher ANC and inferior venous thrombosis-free survival in both ET (p=0.01) and PV (p=0.007) was sustained during multivariable analysis that included history of venous thrombosis, age and sex; the only other variable of significance was older age in ET (p<0.001). The significant association between ANC and venous thrombosis-free survival was also noted in an external cohort of PV patients from the University of Florence (n=576). Conclusions: The current study identifies ANC as having a direct correlation with venous thrombosis in both ET and PV, independent of currently known risk factors. An additional risk contribution from AMC was apparent for events occuring at or prior to but not after diagnosis. Taken together, these observations flag both neutrophils and monocytes as potential contributors to venous but not arterial thrombosis in MPN, at least not by themselves. Additional collaborative studies are ongoing in order to integrate and reconcile our observations in the context of neutrophil/lymphocyte ratio (Carobbio et al) and JAK2V617F allele burden (Loscocco et al), on venous thrombosis-free survival in PV, reported in concomitantly submitted ASH 2021 abstracts, especially in light of the relatively small number of events in the current study. Disclosures Barbui: Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; AOP Orphan: Membership on an entity's Board of Directors or advisory committees, Research Funding. Vannucchi: AbbVie: Membership on an entity's Board of Directors or advisory committees; Incyte Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees.

Abstract Background Current NCCN and ELN guidelines lack supporting evidence in regards to initiation of cytoreductive therapy in essential thrombocythemia (ET) with extreme thrombocytosis (ExT) ≥1500 x 10 9/L (NCCN guidelines: myeloproliferative neoplasms, version 2. 2019, Barbui, Leukemia, 2018).; we sought to determine prevalence and establish phenotype and genotype correlates for ET with ExT and assess its impact on thrombotic and bleeding events, in the context of aspirin therapy or cytoreduction. Methods 1,249 WHO-defined ET patients evaluated over five decades (1967-2021) were retrospectively recruited from the Mayo Clinic. Conventional criteria were used to define major arterial and venous thrombosis and major hemorrhage. Conventional statistical methods were applied using JMP Pro 14.0.0 software package, SAS Institute, Cary, NC. Results i) Phenotype and genotype correlates Among 1,249 consecutive patients with ET, 104 (8%) displayed Ext ≥1500 x 10 9/L, at time of initial diagnosis; these patients were characterized by younger age (median 47 vs 59 years; p<0.001) female gender (80% vs 62%; p<0.001), CALR mutation (39% vs 25%; p=0.004), lower hemoglobin (median 13.1 vs 13.7 g/dl; p<0.0001), leukocytosis ≥11 x 10 9/l (42% vs 23%; p<0.0001), and palpable splenomegaly (22% vs 14%; 0.03); multivariable analysis confirmed associations with age, anemia, leukocytosis, and CALR mutation. Acquired von Willebrand syndrome was reported in 4/9 (44%) vs 27/78 (35%) tested patients, with or without Ext ≥1500 x 10 9/L, respectively (p=0.57); however, comparison using platelet ≥1000 x 10 9/L resulted in near-signficant difference (46% vs 29%; p=0.11). NGS was performed in 297 patients and showed a non-sigificant association with U2AF1 mutations (5% vs 0.4%; p=0.11). ExT ≥1500 x 10 9/L was present in 25/986 (3%), 42/891 (5%), and 15/558 (3%) in the validation cohort; the limited number of cases precluded comparative analyses. ii )Correlation with vascular events at/prior to diagnosis Arterial or venous thrombosis at/prior to diagnosis occurred in 190 (15%) and 111 (9%) patients, respectively, and major hemorrage in 50 (4%). Ext ≥1500 x 10 9/L was associated with major hemorrhage (HR 2.9; 1.3-6.3), but not with arterial (p=0.15) or venous (p=0.41) thrombotic events, at/prior to diagnosis. Instead, multivariable analysis for events at/prior to diagnosis identified male gender (p=0.02), JAK2 mutation (p=0.01), and cardiovascular risk factors (p=0.001) as risk factors for arterial thrombosis and JAK2 mutation (HR 2.8; 1.4-5.7) as a risk factor for venous thrombosis. iii ) Correlation with vascular events after diagnosis At median follow-up of 10 years, arterial or venous thrombosis occurred in 222 (18%) and 97 (8%) patients, respectively, and major hemorrage in 128 (11%). Ext ≥1500 x 10 9/L at diagnosis was not associated with arterial (p=0.35) or venous (p=0.23) thrombosis-free survival or hemorrhage-free survival (p=0.24). Instead, multivariable analysis identified age >60 years, presence of cardiovascular risk factors, and history of arterial thrombosis, as risk factors for arterial thrombosis-free survival; and male gender and history of venous thrombosis as risk factors for venous thrombosis-free survival; and age >60 years and leukocytosis of ≥11 x 10 9/L as risk factors for hemorrhage-free survival. In addition, aspirin therapy was idependently protective of venous thrombosis (HR 0.5; 0.2-0.9), and also of arterial thrombosis, in univariate analysis (HR 0.6; 0.3-0.9), without being associated with an increased risk of major hemorrhage (p=0.64); by contrast, beneficial effect from cytoreductive therapy was not evident for either arterial (p=0.37) or venous (p=0.77) thrombosis. In low-risk patients with Ext ≥1500 x 10 9/L, both aspirin and cytoreductive therapy were protective of venous events (Figure 1), without affecting hemorrhage-free survival. Conclusion ExT ≥1500 x 10 9/L in ET was associated with major hemorrhage at diagnosis but did not affect thrombosis-free or hemorrhage-free survival. Initial therapy with aspirin and/or cytoreductive therapy was protective of venous events in ET patients with ExT ≥1500 x 10 9/L, including those with low-risk disease, without enhancing the risk of hemorrhage. The limited number of informative cases with ExT in the validation cohort, underscore the foreseeable challenges associated with controlled studies. Figure 1 Figure 1. Disclosures Szuber: Novartis: Honoraria. Vannucchi: AbbVie: Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Incyte Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees. Barbui: AOP Orphan: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Abstract Background The recent association of cerebral venous thrombosis (CVT) with COVID-19 vaccinations (JAMA; 2021; 325, N Engl J Med 2021; 384) motivated the current review of CVT and MPN. Our objectives were, i) provide an estimation of the incidence of CVT in the context of MPN, followed by a description of clinical phenotype and therapeutic strategies, ii) determine long term outlook in terms of recurrent thromboses, hemorrhage, and survival, iii) identify salient features which distinguish MPN associated from COVID vaccine- related CVT. Methods 74 consecutive MPN patients with CVT that underwent evaluation at the Mayo Clinic, Rochester MN, USA (n=36), Catholic University, Rome, Italy, (n=23), and University of Florence, Italy (n=15) between 1991 and 2021 were included. The cohort from a previously published multi-center study that included 42 MPN cases with CVT, which were not included in the current study, was used for comparison of observations. Diagnosis of CVT was established with computed tomography or magnetic resonance imaging with venography. Results Patient characteristics at time of CVT Among 74 patients with CVT and MPN (median age 44 years, range 15-85; 61% females); disease-specific frequencies were 1.3% (39/2,893), 1.2% (21/1,811) and 0.2% (3/1,888) for essential thrombocythemia (ET), polycythemia vera (PV) and primary myelofibrosis (PMF), respectively. CVT occurred prior to (n=20, 27%, median time to MPN diagnosis 16.5 months), at (n=32, 44%) or after (n=21, 29%, median time to CVT 26 months) MPN diagnosis. 72% of patients presented with headaches, 22% visual changes, 12% nausea/vomiting, 8% neurological deficits, and 6% seizures. Transverse (51%), sagittal (43%) and sigmoid (35%) sinuses were involved with central nervous system hemorrhage in 10 (14%) patients. MPN phenotype included ET (n=39, 53%), PV (n=21, 28%), pre-fibrotic MF (n=6, 8%), MPN-unclassified (n=4, 5%), PMF (n=3, 4%) and post-PV MF (n=1, 1%). Driver mutation testing was performed in 65 patients: 91% harbored JAK2V617F, 3% CALR type 1, 2% MPL, 5% triple negative; moreover, JAK2V617F was mutated in 27/33 (82%) ET patients. An underlying thrombophilia was identified in 19 (31%) cases. No patient had thrombocytopenia. (Table 1). Notably, one patient received the Ad26.COV2.S vaccine, five days prior to presenting with CVT, not associated with thrombosis in other sites, thrombocytopenia or platelet factor 4 antibodies. A history of thrombosis was documented in 10 (14%) patients with three splanchnic venous events. These observations were similar to those noted in our comparative group from a previously published report that included 42 cases; (ET (n=25, 60%), PV (n=11, 26%), PMF (n=5, 12%); median age 51 years, range 16-84; 55% females; 81% JAK2V617F mutated). Prior thrombosis occurred in 8(19%) patients with four splanchnic venous events. Treatment for CVT included systemic anticoagulation alone in 27 (36%) patients or in conjunction with aspirin (n=24, 32%), cytoreductive therapy (n=14, 19%), or both aspirin and cytoreduction (n=9, 12%). 5/21 (24%) patients with CVT post MPN diagnosis, were on anticoagulation at the time of CVT. Outcome following CVT At a median follow-up of 5.1 years (range; 0.1-28.6), recurrent CVT was documented in 3 (4%) patients; incidence rates for other arterial and venous thromboses and hemorrhage were 11% (2 per 100 patient-years), 9% (1.9 per 100 patient-years) and 14% (3 per 100 patient-years), respectively. 3 of 7 (43%) venous thromboses were splanchnic events. Antithrombotic therapy was ongoing in 53% and 80% of patients with thrombotic recurrences and hemorrhage, respectively. A higher incidence of venous thrombosis was noted in the aforementioned previously published cohort (12 (29%) vs 7 (9%), p=0.01); with 5/12 (42%) splanchnic events. Incidence rates for arterial thrombosis and major hemorrhage were similar. Fibrotic and leukemic transformation occurred in 5 (8%) and 1(1%) patient, respectively, with five (7%) deaths unrelated to CVT. Conclusions The current study highlights close association of CVT with JAK2V617F, younger age, and female gender. Clinical features distinguishing COVID vaccine-related from MPN-associated CVT include lower likelihood of concomitant non-CVT venous thromboses with the latter; moreover, the absence of thrombocytopenia resulted in a lower rate of intracerebral hemorrhage in MPN cases; as a result, MPN-CVT was not fatal. Figure 1 Figure 1. Disclosures Vannucchi: AbbVie: Membership on an entity's Board of Directors or advisory committees; Incyte Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees.

Summary We describe our single institution experience with cladribine therapy in 42 patients with systemic mastocytosis (SM): 22 advanced (adv‐SM; median age 65 years, 68% males) and 20 indolent/smouldering SM (ISM/SSM; median age 56 years, 45% males); subcategories included eight aggressive, 13 associated with another haematological neoplasm, one mast cell leukaemia, 17 ISM and three SSM. Overall/major response rates were 77%/45% for adv‐SM and 70%/60% for ISM/SSM, and median (range) duration of response 10 (4–75) and 46 (4–140) months respectively. A >50% reduction in bone marrow mast cell burden and serum tryptase level was documented in 63% and 67% of patients with adv‐SM and 50% and 46% with ISM/SSM respectively. The presence of KIT proto‐oncogene, receptor tyrosine kinase ( KIT ) D816V predicted response in adv‐SM: 17 (90%) of 19 with and none of three without the mutation responded ( P < 0·01). Treatment‐emergent adverse events were mostly limited to transient cytopenias: Grade 3/4 neutropenia, thrombocytopenia, or lymphopenia occurred in 27%, 27% and 27% of patients with adv‐SM, and 5%, 5% and 30% with ISM/SSM respectively. The present study provides practical information that might be considered when making treatment choices between cladribine and newer KIT‐targeted therapies and identifies the absence of KIT D816V as a potential marker of cladribine resistance in advanced SM; the latter observation needs confirmation in a larger study.

AbstractThe recent association of cerebral venous thrombosis (CVT) with COVID‐19 vaccinations prompted the current retrospective review of 74 cases of CVT (median age = 44 years, range 15–85; 61% females) associated with myeloproliferative neoplasms (MPNs), seen at the Mayo Clinic, Catholic University of Rome, and University of Florence, between 1991 and 2021. Disease‐specific frequencies were 1.3% (39/2893), 1.2% (21/1811) and 0.2% (3/1888) for essential thrombocythemia, polycythemia vera and primary myelofibrosis, respectively. Cerebral venous thrombosis occurred either prior to (n = 20, 27%), at (n = 32, 44%) or after (n = 22) MPN diagnosis. A total of 72% of patients presented with headaches. Transverse (51%), sagittal (43%) and sigmoid sinuses (35%) were involved with central nervous system hemorrhage noted in 10 (14%) patients. In all, 91% of tested patients harbored JAK2V617F. An underlying thrombophilic condition was identified in 19 (31%) cases and history of thrombosis in 10 (14%). Treatment for CVT included systemic anticoagulation alone (n = 27) or in conjunction with aspirin (n = 24), cytoreductive therapy (n = 14), or both (n = 9). At a median follow‐up of 5.1 years (range 0.1–28.6), recurrent CVT was documented in three (4%) patients while recurrent arterial and venous thromboses and major hemorrhage were recorded in 11%, 9% and 14%, respectively. Follow‐up neurological assessment revealed headaches (n = 9), vision loss (n = 1) and cognitive impairment (n = 1). The current study lends clarity to MPN‐associated CVT and highlights its close association with JAK2V617F, younger age and female gender. Clinical features that distinguish COVID vaccine‐related CVT from MPN‐associated CVT include, in the latter, lower likelihood of concurrent venous thromboses and intracerebral hemorrhage; as a result, MPN‐associated CVT was not fatal.